Methods and systems for tissue processing have been described (see WO 99/09390, WO 01/44783, WO 01/44784, and WO 2005/40763). They required a mixture of at least ketone and alcohol for chemical processing. Here, it is shown that alcohol is not required. A tissue sample can be obtained from a patient during surgery. A specimen thereof can be processed to a tissue block, the block is sectioned, and a tissue section is examined by an anatomic pathologist. Histologic examination of the tissue section and diagnosis are completed prior to the patient leaving surgery. An advantage of the invention over frozen sections is that the morphology of tissue sections viewed under the microscope is preserved in tissue blocks. The quality of sections from a tissue block appears to be the same whether the block was prepared by conventional processing or the invention. Discordant or deferred diagnosis, which is primarily due to artifacts observed during histologic examination of frozen sections, would be avoided by use of the present invention.
Intraoperative pathology consultation involves gross and microscopic examination of a sample obtained from a patient during surgery. Most often, histologic examination of a tissue section under the microscope is carried out by dye staining to examine histomorphology. This is conventionally performed on a “frozen” section from a solid tissue such that diagnosis by an anatomic pathologist is possible prior to the patient leaving surgery (i.e., intraoperatively). See Keeney & Leslie, JAMA 300:1074-1075 (2008). The history of Wilson's development of the frozen section technique was recounted at the centenary of its publication by Gal & Cagle, JAMA 294:3135-3137 (2005) and Lechago, Arch, Pathol. Lab. Med. 129:1529-1530 (2005).
Laboratory accreditation by the College of American Pathologists (CAP) requires that intraoperative diagnosis using a frozen section be confirmed by later study of a so-called “permanent” section obtained from the same tissue, which was previously used to obtain the frozen section, embedded in a paraffin block. From the reports of participants in the CAP Q-track program, there was a discordance between frozen section and permanent section (i.e., an adequate frozen section study with an intraoperative diagnosis that has diagnostic disagreement with the paraffin section) of at least about 1%-2%. See Raab et al., Arch. Pathol. Lab. Med. 130:337-342 (2006). For this reason, as well as delay caused by deferred diagnosis, it would be desirable to provide intra-operative diagnosis of a section from a tissue block prepared by the present invention. But shortening the time required to prepare a tissue specimen for histologic examination from a surgical sample such that intraoperative diagnosis is possible has taken substantial modifications of existing methods and systems.
These improvements in methods and systems for tissue preparation are now described. They are characterized by (i) grossing solid tissue to a uniform thickness of about 0.6 mm and/or (ii) a chemical admixture of at least a ketone and an oil to harden a tissue specimen and/or (iii) a cooler to solidify a block containing a tissue specimen. Preferably, a tissue sample is first contacted with the chemical admixture during grossing to initiate hardening of the tissue and thereby facilitate its slicing into one or more tissue specimens. The lack of histologic artifacts is an improvement over conventional histologic examination of a frozen section that it is known in the art can be expected to produce discordant and deferred diagnoses. The requirement to perform a later study of a permanent section becomes moot because consistent morphology is obtained by the present invention.
Other advantages of the invention are discussed below or would be apparent to a person skilled in the art from that discussion.